The side-effects of SHA-2 and what to do now

Secure Hash Algorithm 1 (SHA-1) is like a math problem that scrambles data put into it. Developed by the United States National Security Agency (NSA) in 1993, it’s a core component of many technologies used to encrypt important Internet transmissions. Browser makers have been racing to migrate from SHA-1 to SHA-2. Why? Because researchers have intensified warnings about collision attacks moving from theoretical to practical.

What’s a collision attack?

To understand the impact of a collision attack (and the significance of SHA-1 coming to an end), you need to know about hash functions. A “hash” is a unique code based on the input of any data. Even a small string of letters input into a hash function like SHA-1 will return a long set number of characters, making it (potentially) impossible to revert the string of characters back to the original data. This is how password storage usually works.

A collision attack is an attempt to find two input strings of a hash function that produce the same hash result. To protect users from collision attacks, since January 24, 2017, Mozilla’s Firefox browser is the first major browser to display a warning to users who run into a website that doesn’t support Transport Layer Security certificates signed by the SHA-2 hashing algorithm.

SHA-2 to the rescue…maybe

Replacing SHA-1, SHA-2 is a family of hashing algorithms that features a higher level of security than its predecessor. It was designed through The National Institute of Standards and Technology (NIST) and the NSA in 2001. One of its major benefits is that it addresses some weaknesses in the SHA-1 hashing algorithm.

Experts warn that the move to SHA-2 comes with a wide range of side effects; from unsupported applications to misconfigured hardware and crippled credit card processing gear. The transition has been confusing and cumbersome to businesses dependent on a growing number of digital certificates used for not only their websites, but data centers, cloud services, and mobile apps. Public websites not supporting SHA-2 will generate warnings cautioning users the site they are visiting is insecure.

Many companies, including Facebook, have sought a stopgap fix until SHA-2 adoption is ubiquitous. For example, Facebook leverages “certificate switching,” where the company intelligently chooses which certificates a person sees based upon Facebook’s guess as to the capabilities of the user’s browser. Cloudflare and Mozilla have both developed similar techniques.

To protect yourself, and your organization, it’s important to follow a regular patching program for your applications, including browsers. This will ensure the tools you use are capable of working with more stringent security requirements.

The problem with apps

When a browser rejects SHA-1 certificate, the warning message is usually easy to spot. That’s not the case with apps. While Google’s Android and Apple’s iOS -have supported SHA-2 for more than a year, most apps still do not. SHA-1 used by apps is a far cry from no protection. But still, the absence of SHA-2 introduces risk that someone could mint a forged SHA-1 certificate to connect with an app using an SHA-1 certificate. An attacker spoofing the DNS of a public Wi-Fi connection could launch a man-in-the-middle attack, and unlike with a browser, the use of untrusted TLS certificates would go unnoticed.

Think of 2017 as the year SHA-2 migrations begin to hit their stride. NextGen Healthcare is committed to using SHA-2 for all of our code signing certificates. If you have questions or want more information about how the transition to SHA-2 may affect you, reach out to us.

Blog Suggestions

NextGen Healthcare helps ambulatory care organizations transition to value-based care by empowering them to nurture measurably healthier patient communities at a lower cost. Our solutions, optimized by physicians, developed with input from our 90,000 providers, and based on almost 25 years of ambulatory expertise, help ease the burdens of HIT and enable practices to improve individual outcomes and nurture a healthier population.